Here’s how the authors broke down the astonishing rise of the 21st century’s gerontocracy:

A radically extended lifespan has been experienced by only four of the 8,000 generations of modern humans that have lived on earth.
A 72-year-old man living in Sweden or Japan today has the same odds of dying as a prehistoric 30-year-old hunter-gatherer.
Prehistoric humans already had a significantly extended lifespan when compared to our non-human primate ancestors, yet the difference between modern and prehistoric humans is even larger.

How silly can you get? Consider living in a cave. Anyone who lives in a cave, probably with high humidity and improper protection from in-ground cold, with bugs and spiders crawling around and biting him, and probably without proper sanitary conditions, increases his odds of dying young. You can find people all over the poor countries of the world who die young because they drink downstream water from the upstream sewage dumpers. If anything, cave people were healthier than we are. Why? Because we'ed die in no time at all, from exposure, if we tried living like they did.